The progress of communication means using electric waves has been amazing. For the electric waves, a high frequency area tends to be used more and more, as the amount of information transmitted increases. For example, a UHF (ultra high frequency) of up to a frequency of 300 MHz is used for wireless LAN (local access network) and cell phones. However for high frequency wireless LAN, satellite communication and cell phone base stations, which will be the center of future development, microwaves of 3 to 30 GHz are used.
In the case of using these high frequency waves, electric characteristics such as stable low dielectric constant (εr) and a low dielectric dissipation factor (tan δ), facilitated process moldability, and also heat resistance which can resist plating and soldering are desired for the material of parts used for the telecommunications equipment such as electric parts including a connector, casing and coaxial cable. Therefore conventionally, fluorine resin excellent in electric characteristics are used.
Examples of the fluorine resin used in telecommunications equipment are, in addition to polytetrafluoroethylene (PTFE) which cannot be melt-processed, a tetrafluoroethylene (TFE) hexafluoropropylene (HFP) copolymer (FEP: containing at least 6.9% by mole of HFP) and a TFE-perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA: containing at least 1.5% by mole of PAVE), which can be melt-processed.
As a result of going through research to improve high frequency electric characteristics in a microwave area, especially lowering the dielectric dissipation factor, and also to improve molding processability, the present inventors discovered that by using a TFE homopolymer (hereinafter “PTFE”) or a copolymer obtained by copolymerizing TFE and a slight amount of a fluorine monomer (hereinafter “modified PTFE”) which is greater in standard specific gravity, in other words by lowering the molecular weight of the PTFE or the modified PTFE, the dielectric dissipation factor can be lowered and furthermore that the PTFE or the modified PTFE has acceptable molding processability.